Liquid crystal display device and method of manufacturing the same

ABSTRACT

The liquid crystal display device includes a liquid crystal display panel, a c-plate mono-axial compensating film, first and second polarizing plates. The liquid crystal display panel includes a first substrate having a first electrode, a second substrate having a second electrode, and liquid crystal interposed between the first and second substrates. The liquid crystal is vertically aligned when no electrical filed is applied between the first and second electrodes. The c-plate mono-axial compensating film is disposed on the first substrate. The first polarizing plate is disposed on the c-plate mono-axial compensating film. The second polarizing plate is disposed on the second substrate. A liquid crystal display device according to an embodiment of the present invention has reduced thickness, weight. Further, the liquid crystal display device has increased luminance and broadened viewing angle.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application relies for priority upon Korean PatentApplication No. 2003-30105 filed on May 13, 2003, the contents of whichare herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal display deviceand a method of manufacturing the liquid crystal display device, andmore particularly to a liquid crystal display device having an enhancedviewing angle and an enhanced luminance, and a method of manufacturingthe liquid crystal display device.

[0004] 2. Description of the Related Art

[0005] Electric field changes an arrangement of liquid crystalmolecules. When the arrangement of the liquid crystal molecules arechanged, a transmittance of the liquid crystal is changed in accordancewith the arrangement of the liquid crystal molecule. A liquid crystaldisplay (LCD) device uses liquid crystal so as to display an image. Theliquid crystal display device may display a black and white image or acolor image.

[0006] The liquid crystal display device includes a pixel electrode anda common electrode. The area of the pixel electrode is very small. Theliquid crystal is interposed between the pixel electrode and the commonelectrode. When electric fields are formed between the pixel electrodeand the common electrode, an arrangement of the liquid crystal ischanged.

[0007] The liquid crystal display device is lighter and smaller than acathode ray tube (CRT) display device. Therefore, the liquid crystaldisplay device is widely used as a display device for a portablecomputer, a watch and a cellular phone. Recently, the liquid crystaldisplay device is used for a television set.

[0008] However, the liquid crystal display device has a narrow viewingangle. Therefore, when the liquid crystal display device is seen at aposition deviated from the liquid crystal display device, a gray scaleinversion occurs or distorted image is displayed. Further, a luminanceof the liquid crystal display device is relatively low.

[0009] In recent years, a Vertical Alignment (VA) mode or In PlaneSwitching (IPS) technology are developed so as to broaden the viewingangle.

[0010] A compensation film for broadening the viewing angle may be usedin the vertical alignment mode liquid crystal display device. Thecompensation film for broadening the viewing angle may be used in theliquid crystal display device adopting the in plane switching technologyso as to widen the viewing angle.

[0011] Various compensation films have been developed. For example, abiaxial film is used so as to broaden the viewing angle in the U.S. Pat.No. 6,515,728 (entitled “Multi-domain liquid crystal display device”).

[0012] A thickness of the biaxial compensating film is about 80 μm and athickness of adhesive layer for attaching the biaxial compensating filmis about 25 μm. The biaxial compensating film is attached on the bothfaces of the liquid crystal display panel. Therefore, a thickness of theliquid crystal display device is increased by a 210 μm. The two biaxialcompensating films increase the thickness of the liquid crystal displaydevice by 160 μm. The two adhesive layers increase the thickness by 50μm. Therefore, a volume and a weight of the liquid crystal displaydevice are increased. Further, when the biaxial compensation film isused, a volume or a weight of other element such as a light guide plate,a case or a liquid crystal display panel may be reduced so as toconstantly maintain the volume or weight.

[0013] Further, when the biaxial compensation film is used, a step ofmanufacturing process is increased, so that the productivity is lowered.

SUMMARY OF THE INVENTION

[0014] Accordingly, the present invention is provided to substantiallyobviate one or more problems due to limitations and disadvantages of therelated art.

[0015] A liquid crystal display device according to an exemplaryembodiment of the present invention includes a liquid crystal displaypanel, a c-plate mono-axial compensating film, a first polarizing plateand a second polarizing plate. The liquid crystal display panel includesa first substrate having a first electrode, a second substrate having asecond electrode, and liquid crystal interposed between the firstsubstrate and the second substrate. The liquid crystal is verticallyaligned when no electrical filed is applied between the first electrodeand the second electrode. The c-plate mono-axial compensating film isdisposed on the first substrate. The first polarizing plate is disposedon the c-plate mono-axial compensating film. The second polarizing plateis disposed on the second substrate.

[0016] In one aspect of the present invention, there is provided amethod of manufacturing the liquid crystal display device. A liquidcrystal display panel is manufactured. The liquid crystal display panelincludes a first substrate having a first electrode, a second substratehaving a second electrode, and liquid crystal interposed between thefirst substrate and the second substrate. The liquid crystal isvertically aligned when no electrical filed is applied between the firstelectrode and the second electrode. A c-plate mono-axial compensatingfilm is formed on the first substrate. A first polarizing plate isattached on the first substrate. A second polarizing plate is attachedon the second polarizing plate.

[0017] A liquid crystal display device according to an embodiment of thepresent invention has reduced thickness, weight. Further, the liquidcrystal display device has increased luminance and broad viewing angle.

[0018] According to a method of manufacturing the liquid crystal displaydevice, a number of manufacturing steps and a manufacturing time arereduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features and advantages of the presentinvention will become more apparent by describing in detail thepreferred embodiments thereof with reference to the accompanyingdrawings, in which:

[0020]FIG. 1 is a schematic cross-sectional view showing a liquidcrystal display device according to an embodiment of the presentinvention;

[0021]FIG. 2 is a schematic view of a pixel of a first substrate of FIG.1;

[0022]FIG. 3 is schematic perspective view of a c-plate mono-axialcompensating film of FIG. 1;

[0023]FIG. 4 is graphs showing a luminance in accordance with aretardation of a c-plate mono-axial compensating film of FIG. 1;

[0024]FIG. 5 is graphs showing a color temperature in accordance with agray scale for two general bi-axial films and for a c-plate mono-axialcompensating film;

[0025]FIG. 6 is a schematic cross-sectional view showing a c-platemono-axial compensating film that is integrally formed with a polarizingplate;

[0026]FIG. 7 is a schematic cross-sectional view showing a c-platemono-axial compensating film that is attached on a polarizing plate viaan adhesive layer;

[0027]FIG. 8A is a cross-sectional view showing a thin film transistorof a first substrate of FIG. 1;

[0028]FIG. 8B is a schematic view showing a thin film transistor of theFIG. 8A;

[0029]FIG. 8C is a cross-sectional view showing a pixel electrodeelectrically connected with a thin film transistor of FIG. 8A;

[0030]FIG. 8D is a schematic view showing a pixel electrode of FIG. 8C;

[0031]FIGS. 9A is a schematic cross-sectional view showing a secondsubstrate of FIG. 1 having no common electrode deposited thereon;

[0032]FIG. 9B is a schematic cross-sectional view showing a secondsubstrate of FIG. 1 having a common electrode deposited thereon;

[0033]FIG. 10 is a schematic cross-sectional view showing a liquidcrystal display panel having no c-plate mono-axial compensating filmcoated thereon;

[0034]FIG. 11 is a schematic cross-sectional view showing a c-platemono-axial compensating material disposed over a liquid crystal displaypanel of FIG. 10;

[0035]FIG. 12 is a schematic cross-sectional view showing a spreadingprocess of a c-plate mono-axial compensating material of FIG. 11; and

[0036]FIG. 13 is schematic cross-sectional view showing a liquid crystaldisplay panel having a polarizing plate.

DESCRIPTION OF INVENTION

[0037] Hereinafter the preferred embodiment of the present inventionwill be described in detail with reference to the accompanying drawings.

[0038] Embodiment of a Liquid Crystal Display Device

[0039]FIG. 1 is a schematic cross-sectional view showing a liquidcrystal display device according to an embodiment of the presentinvention.

[0040] Referring to FIG. 1, a liquid crystal display device 400 includesa liquid crystal display panel 100, a polarizing plate 200 and a c-platemono-axial compensating film 300. The liquid crystal display device 400may includes a back light assembly for supplying the liquid crystaldisplay panel 100 with light.

[0041] The liquid crystal display panel 100 includes a first substrate110, a second substrate 120 and liquid crystal molecules 130.

[0042]FIG. 2 is a schematic view of a pixel of a first substrate of FIG.1.

[0043] Referring to FIGS. 1 and 2, a first substrate 110 includes afirst transparent substrate 112, a pixel electrode 114 and a voltagesupplying part 116. A glass substrate may be used as the firsttransparent substrate 112. The pixel electrode 114 is arranged in amatrix shape on the first transparent substrate 112.

[0044] When a resolution of the liquid crystal display device 400 is1024×768, a number of the pixel electrode 114 is 1024×768×3. The pixelelectrode 114 comprises Indium Tin Oxide (ITO) or Indium Zinc Oxide(IZO). The indium tin oxide and indium zinc oxide are transparent andconductive materials. The indium tin oxide and the indium zinc oxide aredeposited on the first transparent substrate 112 and then patterned,thereby forming the pixel electrode.

[0045] The voltage supplying part 116 is electrically connected with thepixel electrode 114 formed on a first transparent substrate 112. Thevoltage supplying part 116 applies different voltages to each of thepixel electrodes. The voltage supplying part 116 includes a thin filmtransistor 117 and a signal line. The signal line includes a gate busline 1 18 and a data bus line 119. The gate bus line 118 and the databus line 119 are electrically connected with the thin film transistor117.

[0046] The thin film transistor 117 is electrically connected to thepixel electrode 114. The thin film transistor 117 includes a gateelectrode G, a source electrode S, a drain electrode D and a channellayer C. A metal layer deposited on the first substrate 110 ispatterned, so that the gate electrode G is formed. The channel layer Cis formed on the gate electrode G. The channel layer C insulates thegate electrode G from the drain electrode D. Further, the channel layerC insulates the gate electrode G from the source electrode S. Thechannel layer C may be a one layered-structure including only anamorphous-silicon layer or a two-layered structure including anamorphous-silicon layer and an n⁺ amorphous-silicon layer deposited onthe amorphous-silicon layer.

[0047] The source electrode S and the drain electrode D are formed onthe channel layer C. The source electrode S is insulated from the drainelectrode D.

[0048] The signal line includes a gate bus line 118 and a data bus line119. The data bus line 119 is insulated from the gate bus line 118. Thedata bus line 119 is arranged substantially perpendicular to the gatebus line 118. The gate bus line 118 is electrically connected with thegate electrode G of the thin film transistor 117. The data bus line 119is electrically connected with the source electrode S of the thin filmtransistor 117.

[0049] The second substrate 120 faces the first substrate 110. Thesecond substrate 120 includes a second transparent substrate 122 and acommon electrode 124. The second substrate 120 may includes a colorfilter.

[0050] A glass substrate may be used as the second transparent substrate122. The common electrode 124 is formed on the second transparentsubstrate 122, such that the common electrode 124 faces the pixelelectrode 114. The common electrode 124 comprises the indium tin oxide(ITO) or the indium zinc oxide (IZO). The indium tin oxide layer or theindium zinc oxide layer is patterned, so that the common electrode 124is formed. The color filter (not shown) may be interposed between thesecond transparent substrate 122 and the common electrode 124. Indetail, the color filter (not shown) may be formed on the secondtransparent substrate 122, such that the color filter (not shown) facesthe pixel electrode 114. An area of the color filter (not shown) issubstantially equal to an area of the pixel electrode 114.

[0051] In the embodiment described above, the pixel electrode 114 isformed on the first substrate 110, and the common electrode 124 isformed on the second substrate 120. However, the pixel electrode 114 maybe formed on the second substrate 120, and the common electrode 124 maybe formed on the first substrate 110.

[0052] The first substrate 110 is connected with the second substrate120 with a sealant (not shown). The sealant (not shown) is formed alongthe edges of the first substrate 110 and the second substrate 120. Aspace defined by the first substrate 110, the second substrate 120 andthe sealant receives the liquid crystal 130. A cell gap between thefirst substrate 110 and the second substrate 120 is preferably in therange from about 3.75 μm to about 4 μm.

[0053] The liquid crystal 130 may be dropped on the first substrate 110or on the second substrate 120. The first substrate 110 is combined withthe second substrate 120, so that the liquid crystal 130 is interposedbetween the first substrate 110 and the second substrate 120.

[0054] The first substrate 110 may be combined with the second substrate120 firstly. Then, the liquid crystal 130 may be injected between thefirst substrate 110 and the second substrate 120 due to a vacuumpressure of the space. The liquid crystal molecules 130 are verticallyaligned, so that a director of the liquid crystal molecule isperpendicular to the first substrate 110 and to the second substrate 120when no electric field is applied between the pixel electrode 114 andthe common electrode 124. That is, the liquid crystal display devicecorresponds to vertical alignment mode.

[0055] A first polarizing plate 210 is attached on an outer face of thefirst transparent substrate 112. A second polarizing plate 220 isattached on an outer face of the second transparent substrate 122. Anoptical axis of the first polarizing plate 210 may be parallel orperpendicular to an optical axis of the second polarizing plate 220.

[0056] A c-plate mono-axial compensating film 300 is disposed betweenthe first polarizing plate 210 and the first transparent substrate 112.The c-plate mono-axial compensating film 300 may be disposed between thesecond polarizing plate 220 and the second transparent substrate 122.The c-plate mono-axial compensating film 300 increases the viewing angleand the luminance.

[0057]FIG. 3 is a schematic perspective view of the c-plate mono-axialcompensating film 300 of FIG. 1.

[0058] Referring to FIG. 3, the c-plate mono-axial compensating film 300has a first refractive index n_(x), a second refractive index n_(y) anda third refractive index n_(z). The first refractive index n_(x)corresponds to a refractive index in an x-direction of a Cartesiancoordinate. The second refractive index n_(y) corresponds to arefractive index in an y-direction of the Cartesian coordinate. Thethird refractive index n_(z) corresponds to a refractive index in az-direction (or normal direction of the c-plate mono-axial compensatingfilm 300) of the Cartesian coordinate.

[0059] A retardation value R_(th) of the c-plate mono-axial compensatingfilm 300 is described as a following expression 1.

[0060] <Expression 1>

R _(th)=[(n _(x) +n _(y))/2−n _(z) ]·d,

[0061] wherein “d” denotes a thickness of the c-plate mono-axialcompensating film 300, and n_(x)=n_(y)>n_(z).

[0062] The retardation value R_(th) of the c-plate mono-axialcompensating film 300 according to the present embodiment is in therange from about 220 nm to about 270 nm.

[0063] When the retardation value R_(th) of the c-plate mono-axialcompensating film 300 is in the range from about 220 nm to about 270 nm,the viewing angle is broad and the luminance is high. Further, when theretardation value R_(th) of the c-plate mono-axial compensating film 300is in the range from about 220 nm to about 270 nm, a thinner of thec-plate mono-axial compensating film 300 may be used. As a result ofsimulation, when the retardation value R_(th) of the c-plate mono-axialcompensating film 300 is smaller than 220 nm or larger than 270 nm, theluminance is lowered and a gray scale inversion is occurs.

[0064]FIG. 4 is graphs showing a luminance in accordance with aretardation of a c-plate mono-axial compensating film of FIG. 1. Thegraph ‘a’ shows the luminance when a cell gap (or a distance between thefirst substrate 110 and the second substrate 120) is 3.75 μm. The graph‘b’ shows the luminance when the cell gap is 4 μm.

[0065] Referring to FIG. 4, when the retardation R_(th) is in the rangefrom about 220 nm to about 270 nm, the luminance is relatively high.

[0066] In case that a thickness of the c-plate mono-axial compensatingfilm is in a range from about 4 μm to about 5 μm, the retardation of thec-plate mono-axial compensating film 300 is in the range from about 220nm to about 270 nm.

[0067] When the thickness of the c-plate mono-axial compensating film isabout 5 μm, and the thickness of an adhesive layer is about 25 μm, thethickness is about 30 μm that is only one seventh of the thickness 210nm of the two general biaxial films.

[0068] Even when two adhesive layers are formed on both faces of thec-plate mono-axial compensating film 300, the total thickness is in therange from about 54 μm to about 55 μm, which is one fourth of thethickness of the two general biaxial films.

[0069] A c-plate mono-axial compensating material having fluidity isdisposed on the first substrate 110 or on the second substrate 120.Then, the c-plate mono-axial compensating material is spread, so thatthe c-plate mono-axial compensating film of which thickness is in therange from about 4 μm to about 5 μm is formed.

[0070]FIG. 5 is graphs showing a color temperature in accordance with agray scale for two general bi-axial films and for c-plate mono-axialcompensating film.

[0071] The graph ‘c’ corresponds to a color temperature of the twogeneral biaxial films. The graph ‘d’ corresponds to the colortemperature of the c-plate mono-axial compensating film.

[0072] The color temperature (or Kelvin temperature, K) is a physicaland objective criterion of light having a color. Light havingorange-color corresponds to a relatively low color temperature. Lighthaving white-color corresponds to a relatively high color temperature.Light having blue-color corresponds to more high color temperature. Forexample, a color temperature of light emitted from a light bulb is about2,800K. A color temperature of light emitted from fluorescent lamp is inthe range from about 4,500K to about 6,500K. A color temperature ofsolar light at noon is about 5,400K. A color temperature of light ofgloomy day is in the range from about 6,500K to about 7,000K. A colortemperature of light of blue sky is in the range from about 12,000K toabout 18,000K. The color temperature is measured via a colored glass anda standard illuminant.

[0073] Referring to graph c, a liquid crystal display device having thetwo general biaxial films has a very high color temperature, when thegray scale is low. Therefore, an image displayed on the liquid crystaldisplay device has blue tone. When the gray scale becomes higher than16, an image has a color temperature that is similar to the natural(solar) light.

[0074] Referring to graph d, an image displayed on a liquid crystaldisplay device having a c-plate mono-axial compensating film hassubstantially uniform color temperature regardless of the gray scale.

[0075] The c-plate mono-axial compensating film of which thickness is inthe range from about 4 μm to about 5 μm enhances the luminance, andreduces variation of the color temperature, a thickness and a volume ofthe liquid crystal display device.

[0076]FIG. 6 is a schematic cross-sectional view showing a c-platemono-axial compensating film that is integrally formed with a polarizingplate.

[0077] Referring to FIG. 6, a c-plate mono-axial compensating film 300may be integrally formed with a first polarizing plate 210, and thec-plate mono-axial compensating film 300 may be attached on a firstsubstrate 110. The c-plate mono-axial compensating film 300 may beintegrally formed with a second polarizing plate 220, and the c-platemono-axial compensating film 300 may be attached on a second substrate120. That is, the c-plate mono-axial compensating film 300 may beattached on one of the first polarizing plate 210 and the secondpolarizing plate 220.

[0078]FIG. 7 is a schematic cross-sectional view showing a c-platemono-axial compensating film that is attached on a polarizing plate viaan adhesive layer.

[0079] Referring to FIG. 7, a c-plate mono-axial compensating film 300may be attached on the first substrate 110 or on the second substrate120 via a first adhesive layer 310. A first polarizing plate 210 or asecond polarizing plate 220 may be attached on the c-plate mono-axialcompensating film 300 via a second adhesive layer 320.

[0080] For example, a thickness of the first adhesive layer 310 and thesecond adhesive layer 320 may be less than 25 μm so as to reduce athickness of the liquid crystal display device.

[0081] A c-plate mono-axial compensating material may be mixed with anadhesive material and may be coated on the first substrate 110 or on thesecond substrate 120.

[0082] According to the embodiment described above, a weight and avolume of the liquid crystal display device are reduced. Further, theluminance is enhanced, a viewing angle is broadened, and a number ofmanufacturing steps and a time for manufacturing the liquid crystaldisplay device are reduced.

[0083] Embodiment of Method of Manufacturing Liquid Crystal DisplayDevice FIG. 8A is a cross-sectional view showing a thin film transistorof a first substrate of FIG. 1, and FIG. 8B is a schematic view showinga thin film transistor of the FIG. 8A.

[0084] Referring to FIGS. 8A and 8B, a gate metal such as aluminum (Al)or an alloy of aluminum is deposited on a first transparent substrate112 to form a gate metal layer by sputtering method or chemical vapordeposition (CVD).

[0085] The gate metal layer is patterned by a photolithography process,so that a gate bus line 118 and a gate electrode G elongated from thegate bus line 118 are formed.

[0086] Then a gate insulation layer 113 is deposited on a surface of thefirst transparent substrate 112 by a chemical vapor deposition method,such that the gate insulation layer 113 may cover the gate electrode G.

[0087] An amorphous-silicon layer is deposited on the gate insulationlayer 113. An n⁺ amorphous-silicon layer is deposited on theamorphous-silicon layer. A metal layer is deposited on the n⁺amorphous-silicon layer. Then, the amorphous-silicon layer, the n⁺amorphous-silicon layer and the metal layer are patterned so that a thinfilm having a source electrode S, a drain electrode D and a channellayer C, and a data bus line 119 are formed.

[0088]FIG. 8C is a cross-sectional view showing a pixel electrodeelectrically connected with a thin film transistor of FIG. 8A, and FIG.8D is a schematic view showing a pixel electrode of FIG. 8C.

[0089] Referring to FIGS. 8C and 8D, a pixel electrode 114 is formed,such that the pixel electrode 114 makes contact with the drain electrodeD. The pixel electrode 114 comprises Indium Tin Oxide (ITO) or IndiumZinc Oxide (IZO). Then, an alignment film (not shown) is formed on thefirst transparent substrate 112. A groove (not shown) for aligning aliquid crystal molecule is formed on the alignment film (not shown).

[0090]FIGS. 9A is a schematic cross-sectional view showing a secondsubstrate of FIG. 1 having no common electrode deposited thereon, andFIG. 9B is a schematic cross-sectional view showing a second substrateof FIG. 1 having a common electrode deposited thereon.

[0091] Referring to FIGS. 8D, 9A and 9B, a black matrix 123 forshielding a region disposed between the pixel electrodes 114 of thefirst transparent substrate 110 is formed on the second transparentsubstrate 122. The black matrix 123 may have a rectangular shape.

[0092] A color filter 125 is formed on the second transparent substrate122. The color filter 125 is disposed between the black matrixes 123,such that the color filter 125 faces the pixel electrode 114. Aphotosensitive material is mixed with a pigment or with dyes. Thepigment or the dyes have a red color. The photosensitive material mixedwith the pigment or the dyes is coated on the second transparentsubstrate 122, and patterned by a photolithography process, so that aR-color filter 125 a is formed. A G-color filter 125 b having greencolor and a B-color filter 125 c having blue color are formed on thesecond transparent substrate 122 via the same process, respectively.

[0093] A common electrode 124 is formed on the color filter 125. Thecommon electrode 124 comprises Indium Tin Oxide (ITO) or Indium ZincOxide (IZO).

[0094]FIG. 10 is a schematic cross-sectional view showing a liquidcrystal display panel having no c-plate mono-axial compensating filmcoated thereon.

[0095] Referring to FIG. 10, a first substrate 110 is assembled with asecond substrate 120, such that a pixel electrode 114 of the firstsubstrate 110 faces a common electrode 124 of the second substrate 120.For example, a cell gap (or a distance between the first substrate 110and the second substrate 120) is in the range from about 3.75 μm toabout 4 μm.

[0096] Liquid crystal is injected into a space formed between the firstsubstrate 110 and the second substrate 120. The liquid crystal may bedropped onto the first substrate 110 or the second substrate 120, beforethe first substrate 110 is assembled with the second substrate 120.Then, the first substrate 110 is assembled with the second substrate120.

[0097]FIG. 11 is a schematic cross-sectional view showing a c-platemono-axial compensating material 310 disposed over a liquid crystaldisplay panel of FIG. 10.

[0098] Referring to FIG. 11, the c-plate mono-axial compensatingmaterial 310 may be disposed on the first substrate 110. The c-platemono-axial compensating material 310 has fluidity. The c-platemono-axial compensating material 310 may includes an adhesive.

[0099]FIG. 12 is a schematic cross-sectional view showing a spreadingprocess of the c-plate mono-axial compensating material 310 of FIG. 11.

[0100] Referring to FIG. 12, a spreader 301 uniformly spreads thec-plate mono-axial compensating material 310 disposed on a firstsubstrate 110. Then, the c-plate mono-axial compensating material 310 ishardened, so that a c-plate mono-axial compensating film 300 is formed.For example, a thickness of the c-plate mono-axial compensating film 300is in the range from about 4 μm to about 5 μm.

[0101] The c-plate mono-axial compensating film 300 has a firstrefractive index n_(x) a second refractive index n_(y) and a thirdrefractive index n_(z). The first refractive index n, is the refractiveindex of x-direction that is parallel to a surface of the c-platemono-axial compensating film 300. The second refractive index n_(y) isthe refractive index of y-direction that is parallel to a surface of thec-plate mono-axial compensating film 300. The third refractive indexn_(z) is the refractive index of z-direction that is perpendicular to asurface of the c-plate mono-axial compensating film 300. In general, thefirst refractive index n_(x) equals to the second refractive indexn_(y), and the first refractive index n_(x) is larger than the thirdrefractive index n_(z) (n_(x)=n_(y)>n_(z)).

[0102] For example, the retardation R_(th) of the c-plate mono-axialcompensating film 300 is preferably in the range from about 220 nm toabout 270 nm, where the retardation R_(th) is represented by thefollowing equation.

[0103] <Expression 1>

R _(th)=[(n _(x) +n _(y))/2−n _(z) ]·d,

[0104] where ‘d’ is a thickness of the c-plate mono-axial compensatingfilm 300.

[0105] When the retardation R_(th) of the c-plate mono-axialcompensating film 300 is in the range from about 220 nm to about 270 nm,the luminance and the viewing angle have maximum value as shown in FIG.4. According to a result of simulation, when the retardation valueR_(th) is smaller than 220 nm or larger than 270 nm, the luminancedecreases and the gray scale inversion occurs.

[0106]FIG. 13 is schematic cross-sectional view showing a liquid crystaldisplay panel having a polarizing plate.

[0107] Referring to FIG. 13, when a c-plate mono-axial compensating film300 is formed, a first polarizing plate 210 is attached on the c-platemono-axial compensating film 300, and a second polarizing plate 220 isattached on the second substrate 120. An optical axis of the firstpolarizing plate 210 may be in parallel with or perpendicular to anoptical axis of the second polarizing plate 220.

[0108] A liquid crystal display device according to an embodiment of thepresent invention has reduced thickness, weight. Further, the liquidcrystal display device has increased luminance and broad viewing angle.

[0109] According to a method of manufacturing the liquid crystal displaydevice, a number of manufacturing steps and a manufacturing time arereduced.

[0110] While the exemplary embodiments of the present invention and itsadvantages have been described in detail, it should be understood thatvarious changes, substitutions and alterations can be made hereinwithout departing from the spirit and scope of the invention as definedby appended claims.

What is claimed is:
 1. A liquid crystal display device comprising: a liquid crystal display panel including a first substrate having a first electrode, a second substrate having a second electrode, and liquid crystal interposed between the first substrate and the second substrate, the liquid crystal being vertically aligned when no electrical filed is applied between the first electrode and the second electrode; a c-plate mono-axial compensating film disposed on the first substrate; a first polarizing plate disposed on the c-plate mono-axial compensating film; and a second polarizing plate disposed on the second substrate.
 2. The liquid crystal display device of claim 1, wherein a retardation value R_(th) of the c-plate mono-axial compensating film is in a range from about 220 nm to about 270 nm, where the retardation value R_(th) is represented by R_(th)=[(n_(x)+n_(y))/2−n_(z)]·d, n_(x) is a first refractive index according to x-direction, n_(y) is a second refractive index according to y-direction, n_(z) is a third refractive index according to z-direction and ‘d’ is a thickness of the c-plate mono-axial compensating film.
 3. The liquid crystal display device of claim 2, wherein the thickness ‘d’ of the c-plate mono-axial compensating film is in a range from about 4 μm to about 5 μm.
 4. The liquid crystal display device of claim 2, wherein a cell gap of the first substrate and the second substrate is in a range from about 3.75 μm to about 4 μm.
 5. The liquid crystal display device of claim 1, wherein the first substrate corresponds to a pixel electrode, and the second electrode corresponds to a common electrode facing the pixel electrode.
 6. The liquid crystal display device of claim 1, wherein the first substrate corresponds to a common electrode, and the second electrode corresponds to a pixel electrode facing the common electrode.
 7. The liquid crystal display device of claim 1, wherein the c-plate mono-axial compensating film is integrally formed with the first polarizing plate.
 8. The liquid crystal display device of claim 1, wherein the c-plate mono-axial compensating film is attached on the liquid crystal display panel with an adhesive.
 9. A method of manufacturing a liquid crystal display device comprising: manufacturing a liquid crystal display panel including a first substrate having a first electrode, a second substrate having a second electrode, and liquid crystal interposed between the first substrate and the second substrate, the liquid crystal being vertically aligned when no electrical filed is applied between the first electrode and the second electrode; forming a c-plate mono-axial compensating film on the first substrate; attaching a first polarizing plate on the first substrate; and attaching a second polarizing plate on the second polarizing plate.
 10. The method of claim 1, wherein a retardation value R_(th) of the c-plate mono-axial compensating film is in a range from about 220 nm to about 270 nm, where the retardation value R_(th) is represented by R_(th)=[(n_(x)+n_(y))/2−n_(z)]·d, n_(x) is a first refractive index according to x-direction, n_(y) is a second refractive index according to y-direction, n_(z) is a third refractive index according to z-direction and ‘d’ is a thickness of the c-plate mono-axial compensating film.
 11. The method of claim 9, wherein the c-plate mono-axial compensating film is formed by: disposing a c-plate mono-axial compensating material having fluidity on the first substrate; spreading the c-plate mono-axial compensating material so as to form a c-plate mono-axial compensating film; and curing the c-plate mono-axial compensating film.
 12. The method of claim 10, wherein a thickness ‘d’ of the c-plate mono-axial compensating film is in a range from about 4 μm to about 5 μm.
 13. The method of claim 10, wherein a cell gap of the first substrate and the second substrate is in a range from about 3.75 μm to about 4 μm.
 14. The method of claim 9, wherein the first substrate corresponds to a pixel electrode, and the second electrode corresponds to a common electrode facing the pixel electrode.
 15. The method of claim 9, wherein the first substrate corresponds to a common electrode, and the second electrode corresponds to a pixel electrode facing the common electrode. 